Deposition Characteristics of Particles with Different Diameters in an Impingement-Effusion Structure with a Double-Wall Blade

Ingestion and deposition of fine particles on the surface of the coolant passage degrade the blade's cooling performance. This paper proposes a deposition model to investigate the complex deposition characteristics of fine particles during repeated collision, adhesion, rebound, and removal events in the small space inside a typical impingement-effusion structure with a double-wall blade. The results show that the particles rarely collide with the wall and escape directly from the film hole outlet when the particle diameters are smaller than 0.5 & mu;m. Most particles with diameters of 0.5 to 1.0 & mu;m are deposited after the first collision around the stagnation point in an area 0.35 times the pin-fin diameter. Some particles with diameters of 1.0 to 3.0 & mu;m are deposited in the stagnation region, but most are deposited between the two pin fins and near the film hole after the second collision. Particles with diameters larger than 3.0 & mu;m are mainly deposited on the region enclosed by the adjacent pin fins and film holes after multiple collisions, and the escape rate of particles is higher than 30%. The escape rates of particles with diameters of 0.5 to 1.0 & mu;m and 1.0 to 3.0 & mu;m have the same trends, exhibiting a decrease followed by an increase with the increasing particle diameter. The particles entering the impingement-effusion structure, especially those with diameters of 0.7 -0.8 & mu;m and 1.4 -2.4 & mu;m, are primarily deposited on the target surface, resulting in the cooling performance degradation of double-walled blade.